Apparatus for reduction



AUS- 1, 1939- R. s, BUTLER 2,168,082

APPARATUS Foa REDUCTION Filed 0st. 19, 1935 5 Sheets-Sheet l 1.7206732507 Zoerzf SuzfZer AUS- 1, 1939 R. s. BUTLER 2,168,082

APPARATUS FOR REDUCTION Filed Oct. 19, 1935 3 Sheets-Sheet 2 Aug. l, 1939. R. s. BUTLER APIARATUS FOR REDUCTION Filed Oct. 19. 1955 3 Sheets-Sheet 5 Patented Aug. 1,1939

nmssui-:n

SEP 194i UNITED ""PXTENT OFFICE APPARATUS FOR BEDUIXIIGNv neben s. Butler, Claremont, N. n., assigner to Sullivan Machinery Company, a corporation of My invention relates to an apparatus for reducing or crushing materialsyfor example coal.

ores and the like. Among the purposes of myinvention are an increase in eillciency of reduction-` and a minimum use of power, a negligible use of power when the machine is running empty. anda continuous automatic feed whereby the mass undergoing reduction serves to control the admission of new particles to the zone of reduction to take the piace of the reduced particles which escape therefrom. Another purpose is the provision of an apparatus in which the load undergoing reduction is, during the reducing cycle, subjected to substantially constant reducing stress or pressure. As an example, I oscillate or reciprocate a compact load of particles through a defined reducing zone, such zone being dened by an oscillated reduction chamber and including the space within the interior of the chamber at any instant and all the other space within the interior of the chamber in the various positions of the latter as it is moved in the course of its oscillation, and subject the load not merely to longitudinal reducing pressure at 2;, each change of direction of movement. but subject it to transverse reducing pressure intermediate said changes of movement. Another purpose is the provision of an improved reduction machine in which a reducing chamber and a feed passage thereto are unitarily oscillated or reciprooated. during the maintenance of a constant supply of-new particles for reductionas the reduced particles escape from the device. Another purpose is the provision of improved feeding means for an oscillating reduction mill.

Other objects will appear from time to time in the course of the speciiication and claims.

The present vimplication includes material divided from my co-pending applications Nos. 759,902, illed on December 3l, 1934, and 37,804 illed on August 26, i985.

I illustrate my invention more or less diagrammatically in the accompanying drawings, wherein Figure 1 is a horizontal section on the line I--i of Figure 2;

Figure 2 is a vertical section on the line 2--2 of Figure 1;

Figure 3 is a section on the line 3 3 of Figure z Figure 4 is a section on the line 4 4, indicated in both Figures 2 and 3;

Figure 5 is a section corresponding to the section taken along the line 3-3 o! Figure l, with the material undergoing reduction and the reducing charge included, in order to indicate movement of the material in the course of the reducing method herein described;

Figure 6 is a vertical, radial section throug a reducing chamber. showing the chamber empty except for a reducing charge;

Figure i is a similar section, illustrating the' reducing chamber at the end of its travel toward the right, with the load moving toward the right Just prior to the impact caused by the engagel ment of the load with the right end of the chamber;

Figure 8 is a similar view after the reducing chamber has reversed its direction and is moving toward the left, carrying the charge with it;

Figure 9 illustrates the reduction chamber moving toward the left, after its velocity has begun to decrease, and with the load moving away from the right end of the chamber and toward the left.

Figures 10, 1i and l2 are fragmentary sectional views showing modications in chamber structure.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, Figures 1 to 4 illustrate my improved reducing mill, and Figures 5 to 9 inclusive are primarily directed to illustrating the mode of operation or crushing method of the mill. Figs. 10, 11 and 12 illustrate modifications.

Referring to the drawings, and considering ilrstthe movement of the material through my reduction mill, I illustrate, as at A in Figure 5, a mass of material awaiting crushing, which may be supplied in any suitable fashion to the hopper I. It escapes thence along any suitable fixed chute 2, the material passing down this ilxed chute or spout being indicated at B in Figure 5. This fixed spout 2 may be mounted in any suitable fashion in relation tothe housing generally indicated as 3, which housing is mounted upon any suitable base I and is shown as having a circumferential cylindrical wall ii, an end wall or gate l, and an opposite solid end wall 1. formed with the bearing supporting sleeve l which receives anti-frictional bearings 9 for the shaft Ill to which the below-described reduction chamber structure is secured. The shaft i0 is shown as provided with a tapered end II to which is secured what may be called a pen-` dulum structure which includes the outwardly extending yoke or supports i2. Formed integrally therewith is the feed receiving sleeve or stirrup i3 which surrounds but is spaced out wardlyfromthe tapered sleeve Ilwhlchiskeyed to and is locked against the tapered shaft portion Ii. as by the key Il, washer il and nut I1 uson the screwthreaded extension Il of the shaft Secured in any suitable fashion to the supports Il is the reduction or reducing chamber proper, generally indicated as 2|, which includes an outer arcuate wall 2| provided with apertures Il, an inner annular wall 2l, and thickened end walls 2l. The annular walls Il and I8 are herein shown as concentric with the shaft i0, the common center being indicated at X in Pigures 6 to 9 inclusive. l

The inner or upper ,wall 2l of the reduction chamber is provided with feed apertures 2l at the outer end of a feed passage which is bounded on two sides by walls Il. 'Ihe feed passage so formed communicates at its lower end directly with the reducing chamber Il through the apertures I5 and at its upper end directly with the space between the sleeves Iland Il through an opening I1. Itwillbeseen,asinl"lgures3and5, that the outer sleeve I t is open at its upper side, as at Il, this opening being masked by the arcuated shield or saddle 3i associated with the lower end of the feed spout l. The outer sleeve Il at its lower side has the opening 21 communieating through the feed passage with the apertures 2B. It will be clear. as from Figure 5, that the mass of feed material B is in communication with. and rests upon the mass of feed lmaterial C within the sleeve i3. This in turn rests upon the mass of feed material D in the feed passage defined by the walls It. By reason of the sweeping of the upper surface of material C. as the reduction chamber swings, back and forth beneath the lower end of the column of material B, there will be a sise-reducing operation effected.

The load in the reduction chamber III is generally indicated as at E in Figures 5, '1. B and 9. I'he charge of reducing media, shown as stratied or classied, for reasons which will later appear, includes balls or particles of maximum size G, partiQie-sxfnlntermediate sine G--l and particles of um size G2. These have associated with them, and work against, particles undergoing crushing of maximum size H, intermediate size H-I and minimum size In. The fully reduced particles escape through the apertures Il in the lower or outer reduction chamber wall i and are indicated as at I, falling within the h using 5 and into the discharge hopper 35 which communicates with any suitable discharge spout or chute I6.

In the employment of the mill I impart a rotary oscillation to the reducing chamber 2l about the axis X of the shaft Ill. This movement might be imparted to the reduction chamber in a variety of ways but I illustratemeans for obtaining this oscillation. for example in Figures l to 4. Il indicates a drive shaft which is keyed to the drive pulley 4I, about which may pass any suitable belt. to a power source not herein shown. The shaft Il may be supported for example in anti-frictional bearings l2 and 43. 'Ihe bearings l2 are mounted on any suitable support 44, secured to the base 4. The bearings 4l are mounted in a sleeve l5, herein shown as formed integrally with a closure plate I6 secured in any suitable manner to the generally vertical housing wall 41 in which. also. the shaft ill is rotatably mounted as by the bearings ta. The opposite side of the housing so formed is closed. as by the wall 1 of the reduction chamber housing 5. which Wall snoepen extends outwardly as at 4l and is connected to the wall I1 as by any suitable side and end wall structure Il.

Positioned within the housing so formed, and formed integrally with the end of the shaft lll. is a vdisc il to which is adiustably secured. for rotary adjustment, an inner inset disc Il. Outwardly projecting from this inset is the eccentric stud 52 surrounded by the anti-frictional bearings 53 which in turn are surrounded by the eye l5 of an oscillating arm or connecting rod Il. This arm is plvoted at its outer end as at 50 to a crank arm l1 secured tothe shaft lil. It will therefore be understood that when the shaft Il is rotated in response to any suitable driving connection, the'discs 5l and Ii rotate and move the stud 52 through a circular path. rl'his circular movement is converted. by means of the connecting rod il and arm 51, to a rotary oscillation of the shaft il. This oscillation is in turn imparted to the reduction chamber 2t, the feed'passage extending thereto and the sleeve il. The sliding connection between the sleeve il and the shield Il maintains a continuous and uninterrupted connection with the mass of material A and B sliding from the hopper I down through the feed spout l. 'I'hus the reduction chamber may be continually oscillated without in any degree interrupting the feed of material thereto.

It will be realized that whereas I have described and shown a practical and operative device, nevertheless many changes may be made in the size, shape, number and disposition of parts without departing from the spirit of my invention. I therefore wish my description and drawings to be taken as in a broad sense illustrative and diagrammatic rather than limiting me to my precise showing.

The use and operation of my invention are as follows:

The broad outline of my invention. and the operation of my reduction mill, will readily be understood, for example in connection with Figures 5 to 9. The material to be reduced is fed from a hopper i. through a fixed feed spout 2, to and through an oscillated sleeve i3, which in turn communicates with the oscillated feed passage bounded by the walls 2B. From this passage the material passes directly to the reduction chamber l0. l

The material through the entire line of feed follows a continuous path. The feed material A, B, in the iixed feed hopper and spout i. I, rests upon the material C in the oscillated sleeve Il, which is continuous with the mass D in the oscillated feed passage. 'Lilus entire line or column of feed rests upon the top of the load E. and the load serves as the means for regulating the feed of new particles to take the place of the particles undergoing crushing, becausethe load. as is clear. for example from Figure 5, masks or un erlies the bottom of the feed passage bounded by the walls I0.

In order to make the operation and characteristics of my mill clear, I will outline briefly, under various heads. the most important characteristics.

Reciprocating a load of media and The oscillation or reciprocation of the reduciil chamber 2l reciprocates a load which includes the particles to be reduced and particles of reducing media. The particles or balls of reducing media G, G-i, G2. are scattered through the massA E of particles undergoing "educticii,` as shown in Figure 5. As the chamocr 20 changes its direction or rotation, its right hand end Il receives the impact of the load, and causes the load also to change its direction of movement. In Figure l the load is about to engage with the right hand end 24 oi the chamber I0. In Figure B the load is being moved toward the left with the chamber. In Figure 9 the chamber has begun to 4slow down and the load is still moving to the left. It will continue to move to the left until it engages the lett end 2l of the chamber. This engagement will force the load to move to the right, and this cycle of movement of the load continues as long as suicient new particles are added to the load to maintain the process. The reduced 4particles I escape through the apertures 22 of the wall 2i and may pass down the hopper 35 and the discharge spout 38.

Load confinement-The chamber 20, at its various positions in the course of its oscillation, defines a reduction zone which includes the interior of the chamber at all normal positions of the chamber. In this reduction zone an intermittent4 centrifugal thrust is maintained downwardly toward the bottom of the zone. The material travels from end to end oi' the zone with a periodic change in the direction of movement caused by the oscillation of the reduction chamber Il. The interior of the chamber proper may be described as a zone of restriction, which is moved through and contained in the larger reduction zone. The load as a whole is coniied in close association with thewalls of the chamber 2i. It is' essential .for maximum emciency, that the general motion of both the reducing media and the material undergoing reduction be confined to a path which conforms generally to the path of the load as a whole, that the particles undergoing reduction may be held in contact with the particles of the reducing medium. Wandering of the load or freedom ofmovement is destructive of ediciency and is prevented by maintaining the load as a relatively compact mass. The cross-section of the chamber 2l along the path of movement of the load is therefore desirably, for some purposes, uniform, and the cross-sectional area at least should be, so far as practicable. maintained substantially uniform. Since in the practice of the invention uneven wear of at least `the outer chamber wall 2| may be anticipated, it will be appreciated that maintenance of anapproximation of uniformity of cross-section and of cross-sectional area is all that can be expected. With the maintenance of cross-sectional area approximately uniform, the only displacements of the bounding surface of the load are those due to compression at the reversals of direction of the load and to centrifugal force. There is a permitted internal displacement going on all the time, because the constituents of the load are never at rest, but the cross-sectional area of the load as a whole approximates uniformity, and in the structures illustrated for use in the practice of the invention there may be, unless and until wear affects the situation, a maintenance of the cross-section substantially constant along the path of the load.

The reducing action continues throughout the cycle-The reducing action is a compound one. It is not limited to the impact or pressure caused by the reversal oi direction of the load at each reciprocation. It continues throughout the stroke in the form of radial or tangential pressure primarily against the bottom 2l of the chamber 2l. In the particular structure shown in the present specification, this continuing reducing pressure or thrust results. for example.

from the centrifugal action caused by the rotary oscillation of the chamber 20 about its axis. The time represented by the reversals of direction is only a fraction of a cycle, and to continue the reducing action throughout the stroke, something must be provided for the charge to work against. By employing an 'arcuate bottom 2i, and by oscillating the chamber 20 as a whole about the center X, I compel the load to move as itwere uphill whenever it moves in relation to the chamber. This causes a tangential thrust or pressure and thus we can say that the load is subjected to three diierent reducing actions. There is in the first place the radial centrifugal pressure of the load against the lower portion of the chamber III. There is the tangential pressure caused by movement of the load in relation to the chamber 20, which causes the load to climb up the ends of the chamber. Finally, there is the impact or compression of the load against the chamber end. At all times, during the cycle of reduction, the load is being pressed against a reacting member which causes pressures to be set up within and on the load. It is probable that some 'l5-per cent of the capacity, in my mill, is produced by pressures operating between the actual reversals or terminal impacts. I ilnd the employment of an arcuate bottom or cham-V ber a convenient means for obtaining my result. 'I'he arc of the chamber need not coincide with the arc of travel of the chamber, as is indicated by the chamber 20' of Fig. 10 whose pivot, indicated by the small unnumbered circle, is below the center from which the arc of the chamber is swept and there is room for much variation in contour. While I prefer a chamber having curvilinear bottom and top walls, it is within the spirit of my invention to employ walls having parts at slight angles to each other, as indicated in the construction of chamber 2l" of Fig. 11; or to employ a chamber having upturned ends which need not be curvilinear, as illustrated by the construction of the chamber 20" of Fig. l2.

Stage reduction-A further advantage and eti'ect of my mill, and one which 'contributes to the ready escape of the reduced particles from the chamber 20 through the apertures I2, is the inherent classifying action due to centrifugal force. All particles 'are thrust centrifugally toward the wall 2i during the intermediate portion of each stroke. The reversal of movement at the end of the stroke, with its interruption of l the centrifugal and the tangential thrust above discussed, allows the particles to re-arrange themselves. As the smaller particles are denser for a given volume than the larger, they tend to displace the larger particles toward the center, and to monopoiize the periphery or exterior or bottom of the crushing zone, because their size permits readier outward penetration in a radial direction. This centrifugal forcetends to drive and to hold every particle out as far from the center of rotation or oscillation as it can go. As will appear, for example in Figures 5 and '7, the ne particles GI of the media and H2 of the work, crowd out against the wall Il. The intermediate sized particles G-I of the media and H-i of the work, occupy an intermediate zone or stratum. The largest particles G of the media and H of the work, are stratiiied at the top of the crushing zone. As reduction takes place, the nner particles sift or escape downwardly through the load and pass out through the apertures 22. The tendency of centrifugal force to move the smaller and denser particles to the periphery is made relatively easy by the continuous reversals of direction of the load as a whole, which favor the progressive reorganization of the particle structure of the load.

Force feed, passage, and discharges-The intermittent centrifugal thrust upon the material undergoing crushing supplements the gravita] movement of particles to the reduction zone, through the reduction zone, and out of the reduction zone, all in connection with the above described classification reduction. 'I'he centrifugal force acts on the material D between the passage walls 26 of the feed passage. 'Ihis mass of material, which is under constant gravital thrust downwardly against the load, has its gravita] thrust intermittently strengthened by a centrifugal thrust. It takes considerable force to drive the feed against the tightly packed mass of balls and particles of the load. When sumcient of the liner particles have escaped to shorten the load and to permit a slight unmasking of the feed aperture bounded by the walls 26, it takes force to drive the feed through this opening in the short time that it is uncovered at the ends of the stroke. This centrifugal action not merely contributes to the feeding thrust and to the carrying of the reduced particles through the load as a whole, but contributes to the tendency of the reduced particles at the bottom of the load to escape through the passages 22. As above pointed'out, this centrifugal thrust would not be so effective if it were not discontinuous. Every reversal of direction of the load E, and of the feed mass D, permits re-arrangement of particles and contributes radically to the eillciency of the centrifugal or tangential thrust. 'I'heir conjoint and successive action is an important feature of my invention, and contributes greatly to the efciency of my mill.

Self regulation of feed and volume-In my mill I provide a constant and self regulated feed. This is of vital importance, because. by using it. I avoid loss of efficiency by underfeeding, with no possible risk of overfeeding. The entire line of feed, including the bodies of material indicated at A, B, C and D in Figure 5, exerts a cumulative pressure upon, and body D actually rests in part upon, the top of the charge E. The material in the hopper I can be piled as high as the operator wishes. The passage 2 may be constantly choked and the entire mechanism run at so-called choke feed." No matter how high the material may be piled in the hopper I, there is no possibility of choking or overfeeding the reduction chamber 20. 'I'he load or chamber contents regulates the entrance rate at every instant. I obtain this result in part by employing a form of chamber such that the load illls the chamber cross-sectlonally throughout the length of the load. My preferred way of obtaining this result is to employ a reduction chamber 2li, the cross-sectional area of which approximates uniformity and which desirably is substantially constant throughout its length. The load E moves bodily back and forth along the chamber 20 without deformation of its bounding surface. The intake passage bounded by the walls 28 is of such length, and is so located that the load itself blocks the inlet when the load volume is at a predetermined maximum. This prevents the penetration of additional particles until sufficient reduced particles have been discharged Vto make room for such additional particles. Ihe instant that enough particles have been discharged to permit the addition of new arcanes particles, such new particles are delivered into the charge from the waiting mass D, by gravital thrust or by the reinforcing centrifugal thrust.

Avoidance of short circuits-Another advantage of my mill, effective in connection with the automatic feed control and the classified reduction above discussed is that it renders practically impossible the passage of unreduced particles through the reduction sone. Virtually all the material. admitted from the mass D must pass through the load and through the crushing media from top to bottom, before escaping from the apertures 22. The small part of the material that enters at either end of the load is caught by the oncoming edge of the load E and is pushed against the chamber wall or the chamber end or both. I maintain the rate of reciprocation or oscillation of the chamber so high that this end material cannot drop through the chamber 2l before the load as a whole, or the crushing medium, overtakes it. This is particularly the case, since the load as a whole is maintained relatively compact and solid, iilling up the entire cross-sectional area of the chamber Il lthroughout the length of the load. As a result oi' this prevention of short circuitlng" the size or quality of the product is independent of the frequency of oscillation. This is of importance, as freeing me oi the necessity of closely adhering to an optimum speed, a matter of necessity in conventional bal and impact mills.

Product size control.-In my employment of a relatively conned or compact load, not only do the constituent particles have a generally fixed relation to each other, as they classify by size, but the same is true of their interstices. I provide suilicient movement within the charge itself to prevent stagnation and to make possible the passage of the particles through the charge. I obtain this result by my alternation of longitudinal and transverse reduction pressure. When the particles classify or stratify by size, as they do, as shown for example in Figure 5, the lower stratum composed of the small media particles G2 and the small work particles H2, serves as a sizing bed because oi' the small size of the interstices between particles. Gniy particles small enough to pass through the interstices oi' this layer can escape through the apertures Il. Simllarly, the higher strata of media and particles size or control the particles passing through to the lower part of the reduction zone. The product ultimately passing through the media is substantially uniform in size. And this size is controlled by the sise of the media particles. The work particles of each Vstratum escape to a lower stratum as soon as they are reduced to a size substantially below the size of the media particles of that stratum. rIherefore, by altering the sise of the media, I can alter the size of the interstices, and control the size of the particles passing through and discharging from the load. All that is necessary in order to effect such a change, is to change the size of the media in the chamber 2l.

Pumping actionP-The form of my chamber I. being such that the load lls it in cross-section, a pumping action is developed at each end of the chamber at each reciprocation of the load. 'I'he load acts like a piston within the cylinderlike chamber. This pumping action serves a twofold purpose: rst, in forcing out material which has been reduced to proper size, thus promoting discharge: and second, compressing air or other su' remaining in that portion of the chamber.

which compression serves to take up some of the shock of contact.

Power saving at 'no l0ad.-Inasmuch as the charge is of small volume in relation to the cubic content of the reduction chamber 20, as shown in Figure 6, and since, owing to the curvilinear shape of the chamber bottom 2|, the charge tends to stay in the bottom of the chamber 20, out of contact with the ends 24, I am able to avoid anyworking contact between the media and the ends 2l of the chamber 2l when the chamber is running empty, or if the load falls below a predetermined minimum. In other words, with insuillcient material present, the bottom of the chamber 2|) will travel beneath the medium, but, the oscillation of the chamber will be insufficient to cause the reduced load to engage the chamber ends 2l. The load is held by gravity in an intermediate or idle position. No reduction takes place. and no wear, other than the slight wear against the bottom 2|. And, what is exceedingly important, no power is consumed except the frictional power of the mechanical system. But this lno load operation involves no delay in the resumption of normal operation. When suilicient material enters to build up the load volume to a size where the ends of the chamber engage the load, action starts again, and reduction takes place and continues as long as enough material passes down between the inlet walls 2B to maintain a sumcient load in the chamber 20. This action is so sensitive, and so certain, that in practice I have been able to cause a mill to operate for a second or two on full load, followed by a second or two of no load. A change of a few cubic inches in chamber contents volume, at the critical point, is enough to throw the machine from full load to no load or from no load to full load, the period of building up or dropping oil.' amounting only to a second or two. In the use of my invention the power consumption is more nearly proportioned to the work done than in any other mill or machine known to me. In practice the Vno load power consumption need not be over ten per cent of the full load power consumption.

While the feature just described has the distinct advantages pointed out. it will of course be understood that the volume of media may be varied at the will of the operator by adding or subtracting balls: and, in any event, the employment of my invention, in its broader aspects, is not dependent upon the employment of any particular or predetermined volume of media.

The feeding arrangement-I find it desirable to feed my oscillating mill near the center of oscillation. The feed opening defined by the walls 26 has the same angular amplitude of movement as the chamber 20. But whereas the charge is reciprocated through a very substantial arc in the chamber 2li, the material in the feed passage is constrained to a much smaller arc by the confining walls 26. I'he feed mass D, therein contained, is not permitted to agitate, and by plugging up the whole feed passage, prevents any unintended retrograde escape of particles from the charge E. It serves as a seal for the top of the chamber f '.i, and assists in maintaining the charge in its desired compact condition.

The shield 3l and the sleeve I3 are advantageous in maintaining a constant feeding connection. The opening is never closed or obstructed, even at the extreme ends of the stroke.

In causing the mass D to serve as a plug or seal for the inlet opening to the chamber 20 I 11nd that employing tapered walls 26 is advantageous. There is no chance for material from the chamber 20 to escape when the mass of material D is present. In the event that this material is used up by underfeeding, the tapered sleeve Il still serves as a baffle. The escape of balls or material is effectively prevented.

The mechanics o] my apparatus and method.- In my opinion the major reduction I obtain results from the lateral thrust against the walls, and especially the bottom wall 2l, of the chamber 20. Pressure on material being reduced is necessary for reduction, but pressure accompanied by movement is vastly more effective than pressure alone. I provide both to a high degree. The centrifugal or radial pressure is due to the partial rotative motion of the load about the axis of oscillation of the chamber 2B. It results in a radial compression of the load, due to its mass, radius and velocity, which is greatest at each stroke when the other pressures below described are at a minimum. My second source of reduction is the inertial or longitudinal pressure developed by the reversal of the load due to the reversal in direction of movement of the chamber 2li. It is not a mere impact, but is smoothed out and extended. Instead of moving my load, without choke or drag, between changes oi' direction, I subject it to a constant pressure intermediate its reversal of direction, as above described. I employ not merely the direct radial thrust or pressure above discussed, but the tangential thrust of the load when it moves in relation to the chamber. It tends to move rectilinearly or tangentially, but is constrained to follow the arc and not the tangent. This tangential thrust, which precedes the terminal impact, robs the terminal impact of some of its sharpness, and also returns to the power source some of the energy put into the mass during the acceleration. The changes in thrust resulting from the alternation between longitudinal or inertial pressure and transverse (radial or tangential) pressure, promote settling and limited movement in the mass without allowing the mass as a whole, or its constituent parts, to move freely about. Another contribution to longitudinal pressure results from my employment of a relatively long load, analogous to the effect of a long string of freight cars. The very length of the load increases the time during which the impact resulting from the reversal of direction is felt through the load as a whole.

By the employment of these various features I am able vastly to reduce power use and power costs, while increasing reduction efficiency. I am able to obtain very accurate sizing, and to vary my sizing at will. In my sizing and in my reduction results I am not closely limited to an optimum rate of oscillation.

It will be understood that whereas I have illustrated a mechanism in which the reduced particles pass down a hopper 35 to an outlet 3B, any suitable means may be employed to return oversize particles, ii any, for recrushing. It is thought to be unnecessary to illustrate a mechanism for this purpose, since elevators, conveyers and 4recirculating devices are well known in the art. I wish to make it clear, however, that my invention is not limited to single pass reduction, but is equally applicable to closed circuit reduction in which part or all of the discharged material is returned to the reduction chamber for further reduction.

It will be understood that when, in the claims, I specify that the reducing chamber is of uniform cross-sectional area from end to end, I am alluding to the ends 2l agaimt which the load abuts and to the substantially constant distance separating the walls 2| and Il, and not to the side walls 20a.

While I have in this application specicaliy described one form and three modifications which my invention may assume in practice, it will be understood that this form and these modifications have been shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

And it will further be understood that whereas in the specification or claims I describe the reduction chamber as being substantially uniform or constant, or generally or approximately uniform in cross-section or in cross-sectional area, from end to end thereof, I wish such terms to be used with sumcient embility to include not only slight variations in cross-sectional area from point topoint along the chamber, such as are inevitable under ordinary manufacturing conditions, but also variations in cross-sectional area resulting from inequality of wear, if any.

And whereas it is desirable that said chamber 2li be of generally constant cross-sectional area from end to end thereof, it will be understood that I consider itwithin the scope of my invention to permit slight variations in cross-sectional area to a degree insufllcient to impede or change the character of the reduction which takes place in such chamber or to preclude the described operation of the chamber contents in regulating feed.

I claim:

l. In a mill, means providing a size-reducing chamber supported for movement back and forth, said size-reducing chamber elongated in its direction of back-and-forth movement. at least approximating uniformity in cross sectional area throughout the major portion of its length, provided with discharge means through which material of small enough size to go through the same may pass while the chamber is in motion,

and having means for the introduction into said chamber during the operation of the mill of material to be processed, including a feed passage communicating with said chamber through an aperture intermediate the ends of the charnber in a wall which extends longitudinally of the latter, and means for moving said chamber back and forth, said chamber of-such dimension between said aperture and the opposite surface of said chamber, said chamber and said aperture of such relative lengths and disposition and said chamber-moving means imparting to said chamber movement at such rate and of such amplitude, that during normal continuous size-reducing operation the chamber load will be reciprocated between the ends of the chamber as a substantially compact mass substantially filling the entire cross-section of the chamber throughout the major portion of its own length and sweeping across the feed aperture and controlling the ingress of material awaiting entrance to the chamber at said feed aperture, and coacting with said feed aperture to preclude the building up of the volume of the ni'ass sumciently to iiil the chamber completely.

2. A mill as defined in claim 1. in which the feed aperture opens through the top wall of the chamber and in which the chamber, at least throughout the major portion of its length, at least approximates uniformity in cross section.

3. A mill as defined in claim 1, in which the sine-reducing chamber is supported for arcuate movement and has its walls respectively nearest to and farthest from the axis of its arcuate movement arcuate, in which said chamber at least approximates uniformity in cross section throughout the maior portion of its length on planes including its axis of arcuate movement, and in which the feed aperture lies in the wall nearest the axis of chamber movement.

4. A mill as defined in claim l, in which the chamber is of a dimension longitudinally at least three times its dimension between the feed aperture and the opposite surface of the chamber, and in which said chamber is also of a dimension longitudinally at least three times the dimension of the feed aperture longitudinally of the chamber.

5. In a mill, means providing a size-reducing chamber supported for back-and-forth movement, said size-reducing chamber elongated in its direction of back-and-forth movement, approximating uniformity in cross sectional area throughout the major portion of its length, provided with discharge means for the elimination from the chamber contents during operation, of material below a predetermined sise, and having feed ingress means between its ends having associated therewith supply means adapted to deliver material to said feed ingress means at a rate in excess of the size-reducing capacity of the mill, and means for moving said chamber back and forth, said chamber of such dimension normal to its path of movement, and said chamber-moving means imparting to said chamber movement at such rate, that the contents of said chamber are maintained substantially compact in a mass conforming to the cross section of said chamber, and said chamber and said feed ingress means of such lengths and relative disposition and said chamber-moving means imparting to said chamber such movement both as to velocity and amplitude that with material constantly maintained at said feed ingress means and awaiting entrance to said chamber the chamber contents are reciprocated between the ends of said chamber and maintained insuillcient completely to fill the chamber but sufiicient 'to maintain said chamber substantially filled in cross section at its central portion at all times.

6. In a reduction mill, a reduction chamber arcuate in vertical longitudinal section and at least approximating uniformity in transvei cross sectional area throughout substantially its full length from end to end, means for delivering to said chamber the material to be reduced, means for withdrawing from said chamber the reduced particles. and means for swinging said chamber about a transverse axis, the length and radial dimension of said chamber, its path of swing, and its speed of movement predetermined to maintain the chamber contents in a relatively compact mass, lling substantially the full cross sectional area of said chamber for more than half but less than the entire chamber length, in all of its various positions in said chamber, and to subject said chamber contents through movement by and relative to said chamber successively to radial, tangential and longitudinal pressure.

7. In an apparatus of the character described, an oscillating chamber having a curved internal bottom surface at least approximating in curvature an arc whose center coincides with the axis of oscillation of said chamber and having an upper bounding surface of at least approximately concentric curvature provided with a feed intake opening and having further abutment-providing ends, said chamber at all points between its ends at least approximating uniformity in dimension radially, said dimension materially less than the distance between the axis of chamber oscillation and the point most adjacent thereto in said curved internal bottom surface.

8. In a mill, a movably mounted size-reducing chamber supported for movement in opposite directions along a predetermined path, said chamber elongated and substantially arcuate in its planes of movement and of a uniform width internally throughout its length and of comparatively small but uniform dimension normal to its path of travel, means for introducing' material into said chamber including a feed opening substantially midway between its ends, means for discharging processed material while said chamber is in motion, and means for moving said chamber oppositely along said path, the length of said chamber, its dimension normal to its path, the dimension of said leed opening longitudinally of said chamber and the rate and amplitude of movement of said chamber such that when said mill is operating at capacity during each movement of said chamber in one direction along its path the same is lled completely full throughout the central zone of its length while both ends thereof are empty, whereby the chamber contents control the feed.

9. In a reduction mill, a reducing chamber the cross sectional area of which at least approximates uniformity from end to end of the chamber, means for imparting rotary oscillation to said reducing chamber about a generally horiaantal axis positioned above the reducing chamber, the upper and lower walls of the reducing chamber being at least approximately concentric and struck from said axis and further being of substantially equi-angular arcuate extent, a feed passage opening through the upper wall of said reducing chamber, and means for maintaining feed therethrough during the oscillation of the reducing chamber, the lower wall of the reducing chamber being apertured to permit the escape of the reduced particles.

10. In a mill, a size-reducing-chamber-providing member mounted for pivotal movement about a horizontal axis, means for imparting thereto rapidly alternated arcuate movements in opposite directions, said chamber-providing member having an arcuate chamber formed therein of an angle of arc materially greater than the angle of such arcuate movements, said chamber having end walls and longitudinally extending walls and of substantially uniform cross section, between said end walls, on radial planes, and said longitudinally extending walls including relatively closely spaced concentric inner and outer walls, the rate of chamber movement and the spacing of said concentric walls so predetermined that the chamber movements cause the chamber contents to contact the opposite ends of said chamber in alternation and concurrently to contact, with substantially equiangular extent, said inner and outer walls, during size-reduction.

ll. In a mill, a size-reducing-chamber-providing member supported for arcuate movement about a substantially horizontal axis, and means for imparting there to a rapid oscillation upon such axis, said member providing end walls and between the latter a size-reducing chamber of generally uniform cross sectional area at substantially all points between said end walls on planes including said horizontal axis, and having upwardly concave generally concentric upper and lower Walls with a feed opening through the said upper wall adjacent the center thereof and with said walls so spaced radially that with said feed opening entirely closed by a. level surface of chamber contents resting on the outer wall of said chamber said chamber still provides material room for the reciprocation therein of such contents.

12. In a mill, a size-reducing-chamber-providing member mounted for swinging movement upon a substantially horizontal axis and providing an arcuate chamber having end walls and at least approximately concentric inner and outer walls and at least approximating uniformity in cross sectional area on transverse planes `normal to said concentric walls at substantially all points between said end walls and of such extent and curvature that a straight line connecting the central points in the ends of said chamber falls at its middle point above the central point in the curve of the inner wall of said chamber, means for supplying material to said chamber during oscillation thereof and for discharging processed material therefrom also during operation, and means for oscillating said member rapidly about its pivot through a path such that the central point in the curve of the inner wall of said chamber always lies below a horizontal plane including said horizontal axis, said chamber having the interior thereof clear from end to end thereof for the free movement along said outer wall, under movements imparted thereto by said end walls, of the chamber contents.

13. In a mill, means providing a size-reducing chamber supported for swinging movement, said size-reducing chamber elongated in its direction of swinging movement and having upturned portions at opposite sides of its center as viewed from the side, of at least approximately uniform cross sectional area throughout at least the major portion of its length, provided with discharge means for size-reduced material through which adequately small material may freely pass while said chamber is in motion, and having leed ingress means between its ends having associated therewith supply means adapted, while said chamber is in motion, to deliver material to said feed ing'ress means at a rate at least equal to the sizereducing capacity of the mill, said chamber having walls enclosing the same imperforate save for said discharge and feed ingress means, and means for oscillating said chamber through such an arc that its ends are both always higher than an intermediate portion, said chamber of approximately uniform dimension from end to end normal to its path of movement and of a length at least twice its dimension normal to its path of movement, and the ratio of chamber length to the length, longitudinally of said chamber, of said feed ingress means and the rate of chamber oscillation such that the chamber contents are reciprocated in a substantially compact mass within said chamber in contact with and sustaining the head of material in said supply means .awaiting ingress to said chamber.

14. In combination, a support, a power-oscillated supporting element swingably mounted in depending relation on said support, and a milling chamber iixed to said supporting element for arcuate movement thereby. said milling chamber having concentric upper and lower walls with a feed opening in its upper wall in the longitudinal central portion thereof and with the end portions of said upper wall closed and with its lower wall traversed largely throughout its length with discharge openings, the ends of said chamber substantially diametrically opposite each other with reference to the arc of swing of said chamber and said chamber of generally uniform cross sectional area substantially throughout its length on planes including its center of curvature and of a radial dimension materially lessthan half the radius with which its bottom is formed.

15. In a mill, means providing a size-reducing chamber supported for oscillatory movement about a pivot, said size-reducing chamber elongated in its direction of oscillatory movement and having relatively high ends and a low median portion, approximating uniformity in cross sectional area throughout the major portion of its length, provided with discharge means for sizereduced material through which material of small enough size may pass while said chamber is in motion. and having feed ingress means between its ends having associated therewith supply means of a construction to deliver material to said feed ingress means at a rate in excess of the size-reducing capacity of the mill and under a centrifugal force as a result of the movement of said chamber, said chamber having walls enclosing the same imperforate save for said discharge and said feed ingress means, and means imparting such an oscillation to said chamber as to compact the chamber contents alternately against the chamber ends, leaving the other ends empty, and cause the same to exert a substantial centrifugal force against the outer wall of said chamber during transit from end to end thereof, said chamber of approximately uniformY dimension from end to end normal to its path of movement and of a length beyond either end of said feed ingress means greater than said dimension normal to its path of movement.

16. In a mill, a chamber-forming member supported for oscillatory movement and providing an elongated, relatively shallow chamber having ends materlalhr higher than its median portion when said chamber is in its mid position and adapted to contain during operation a load comprising mingled size-reducing media and material to be redud in size and having its interior free from obstructions to the free movement of such load longitudinally within said chamber under forces imparted thereto by the chamber ends. means for imparting to said chamber-forming member rapidly-alternated opposite movements of a speed and amplitude to cause bodily movement o! the chamber contents as a mass relative to the chamber, in frictional contact, under centrifugal force, with the lower wall of said chamber, and compacting of the chamber contents alternately at the opposite ends of the chamber and the occupancy of thespace therein from top to bottom of said chamber throughout more than half but less than the entire length thereof. and a ieee opening into said chamber across which the chamber contents sweep during movement relative to the chamber.

17. In a mill, means providing a size-reducing chamber supported for reciprocatory movement. said sise-reducing chamber elongated in its direction of reciprocatory movement, of substantially uniform cro. sectional area throughout its aieaosa central and at least the maior remaining portions of its length, provided with discharge means eii'ective to discharge material small enough to pass therethrough, upon the attainment of such material thereto, while the chamber is in motion. having associated therewith supply means for material to ne reduced, and having a feed opening between its ends with which said supply means communicates, and means for imparting to such chamber reciprocatory motion. said feed opening of such dimension longitudinally of said chamber relative to the overall chamber length, and said chamber reciprocating means imparting to said chamber motion of such amplitude and at such speed that the chamber contents are caused to move as a relatively compact mass alternately with, and between the ends of, said chamber and to assume and maintain a volume adequate at least to ll the space within said chamber at one end of said feed opening and also substantially the entire space opposite said feed opening while leaving a substantial unfilled space within said chamber, whereby with material constantly maintained at and awaiting admission through said feed opening, relative reciprocation between the chamber contents and said chamber takes place and the chamber contents regulate the introduction of new material.

i8. In a mill. means providing a sise-reducing chamber supported for reciprocatory movement, said size-reducing chamber elongated in its dlrection of reciprocatory movement. 4approximating uniformity in cross sectional area throughout the major portion oi' its length. provided with discharge means through which material of small enough size may pass while said chamber is in motion, and having feed ingress means between its ends having associated therewith supply means adapted to deliver. while said chamber is in motion, material to said feed ingress means at a rate in excess of the size-reducing capacity of the mill, and means for reciprocating said chamber. said chamber of such dimension between said feed ingress means and the opposite side of said chamber, said chamber and said feed ingress means of such relative lengths and disposition. and said chamber reciprocating means imparting to said chamber movement of such rate and amplitude that with material constantly malntained at said ingress means and awaiting ingress to said chamber the chamber contents are maintained automatically, while said mill is in operation, suiilciently less in volume than the volume of said chamber so that relative reciprocation between said contents and said chamber may take place, but yet adequate in volume to occupy at least one-half the overall length of said chamber throughout its entire cross section, during Vnormal mill operation.

i9. In a mill, a frame, a pendulum pivotally supported on said frame for oscillatory movement about a pivot and having an elongated sisereducing chamber therein oi' approximately semiannular form disposed with its concave side towards said pivot, said pendulum further providing a feed passageopening `into said chamber at a locus which is substantially equally spaced fromtheendsofsaidchamberandatthe same distance as said chamber ends from said pivot, discharge means for sise-reduced material along the wall of said chamber more remote from said pivot, a quantity of free size-reducing media in said chamber. and means for imparting to said chamber alternate opposite movements of an amplitudeand atavelocitytothrowthe chamber y charge means for size-reduced material through Yso which adequately reduced material may freely pass while said chamber is in motion, and having feed ingress means between its ends having associated therewith supply means adapted to deliver material to said feed ingress means at a rate at least equal to the sizereducing capacity of the mill, said chamber having walls enclosing the same imperforate save for said discharge means and feed ingress means and being clear from end to end thereof for the free movement of its contents between its ends, and means for oscillating said chamber through such an arc `that its ends are both always higher than an intermediate portion, said chamber of substantially uniform dimension from end to end normal to its path of movement and of a length a pluralityofttignes its dimensional normal to its path of movement.

21. In a mill, a chamber-forming member providing an elongated relatively shallow chamber having end walls and of like cross section substantially throughout its length between said end walls and adapted to contain during operation a load comprising mingled size-reducing media and material in process, means for imparting to said chamber-forming member rapidly-alternated opposite movements `along a predetermined arc to which the chamberin said member generally conforms in curvature and of a speed and amplitude to cause bodily movement of the chamber contents as a mass relative to the chamber and packing of the chamber contents alternately against the opposite ends of the chamber while the opposite chamber ends are respectively empty, and maintenance of said chamber contents in a substatnially compactlmass at all times iilling throughout its own length substatnially the full chamber cross section, and means providing a'. feed supply connection having a feed-opening into said chamber in a position spaced from the ends of said cham-.- ber and covered by the chamber contents as the latter move between the chamber ends.

22. In a mill, means providing a reversely arcuately moved chamber generally arcuate in its planes'of movement and approximating uniformity in cross section on planes including the axis of movement of such chamber at substantially all points between its end portions, having a feed connection terminating in an intake opening through a wall of said chamber, and a charge of free size-reducing media in said chamber, said size reducing media and material admitted through said feed opening forming a mass moving as a whole from end to end of said chamber and traveling alternately back and forth across said opening while said mill is in operation and acting as a gate therefor.

23. In a reduction mill, a reducing chamber having concentric upper and lower arcute walls and a cross sectional area which is substantialbY uniform from end to end, the ends of said reducing chamber being upwardly turned, a feed passage having communication with said reducing chamber through the upper wall of the latter at a point lower than the opposite extremities of 4 said upper wall, the longtiudinally opposite walls of said passage tapering upwardly and inwardly toward each other, said chamber having the upper walls of its upwardly turned ends each of at least as great extent as the length of the communication with said chamber of said feed passage, and means for imitarily swinging the reducing chamber and feed passage about a center adi acent the upper end of said feed passage and from which said chamber is materially spaced at all points.

24. In a reduction mill, a generally curvilinear reducing chamber mounted for oscillatory movement about a generally horizontal axis, the cross section of said chamber being substantially constant from end to end, the ends of said reducing chamber having a substantial upward extension, means for imparting rotary oscillation to said chamber about said axis, the bottom wall of said chamber being provided with apertures to permit the escape of reduced particles, a feed passage member extending upwardly from the upper wall of said chamber to a point adjacent the axis'of rotation of the chamber, said reducing chamber closed at its top except for communication through said feed passage member, a fixed feed spout, and means Vincluding relatively osciliatable parts nxed respectively relative to said feed spout and to said feed passage member for maintaining a constant feed connection between said fixed feed spout and said feed passage during the rotary oscillation of said chamber.

25, A rocker including a barrel, a feed neck fixedto said barrel and in communication with the interior thereof, and an oscillating milling chamber fixed relative to and in communication with the interior of said feed neck, said barrel cut away at the upper portion thereof, a stationary saddle covering said barrel and in close adjacency thereto and having a feed opening therethrough registering with the cut-away portion/ of said barrel, and means for supplying material to said saddle for delivery through the feed opening thereof into said barrel and through said feed neck into said milling chamber.

26. Ina mill, a saddle having a feed opening therethrough and means for supplying material to said opening; a barrel fitting said saddle and having material-conducting passage means therein communicating with said opening. a support member in rigid relation to said barrel and oscillatable therewith about the axis of said barrel and providing an elongated arcuate size-reducing chamber and a radial feed passage connecting said material-conducting passage means and the interior of said chamber, a charge of size-reducing media. in said chamber. and means for imparting rapidly reversed, pivotal movement to said barrel and support member to effect a sirereducing process throughout said chamber, at the zone of communication of said feed passage with said chamber, and also adjacent the communication between said saddle and said barrel.

27. In a reduction mill, a reducing chamber mounted for oscillation about a generally horizontal axis, said reducing chamber conforming generally in curvature to an arc struck from a point in said axis, thecross section oi' said chamber being approximately constant from end to end, means for imparting to said chamber rotary oscillation about said axis, the outer wall of said chamber being provided with apertures to permit the escape of reduced particles. a feed passage member extending upwardly from the upper wall of said chamber, a sleeve associated with the upper end of said feed passage member, surrounding the axis of oscillation of the chamber. a fixed feed spout, a guard member associated therewith, in relatively rotary shielding relation with said sleeve, said guard member and sleeve being apertured in line withA each other. the apertures of the sleeve and guard being of sumcient size and their relative movement such as to maintain a feed connection between said feed spout and said sleeve of constant cross sectional area.

28. In a reduction mill, an elongated reducing chamber having end walls and longitudinally extending top, bottom and side walls and of approximately uniform cross sectional area between the end portions thereof, means for feeding material thereto including a feed aperture in, and adjacent the central portion of, one of said longitudinally extending walls of said chamber, discharge apertures in another longitudinally extending wall of said chamber, the walls of said chamber imperforate save for said feed and discharge apertures, means for supporting said chamber for oscillation about an axis from which it depends, means for imparting a predetermined longitudinal bodily oscillation to said chamber about said axis, said chamber so formed that the end portions thereof are spaced from each other by less than the length of said chamber along its center line and the end portions of said chamber being upwardly extended relative to the central portion thereof to such a degree that during chamber oscillation the extremities of said chamber are both at all times higher than the lowest intermediate portion thereof, and a charge of free reducing media confined in said chamber by the walls thereof and movable bodily with and also relative to said chamber and insufficient in volume, in relation to the length of excursion of said chamber. to engage either of the chamber ends when the mill is running below a predetermined minimum load.

29. An oscillating size-reducing chamber having upwardly concave arcuate top and bottom walls and further having end walls which alternately engage the chamber contents once in each cycle during milling, said chamber containing a charge of freely movable size-reducing media all of which are free to move relative to each other in any direction except as restricted by the chamber walls and each other and whose most remote elements are spaced from each end of the chamber when the latter is stationary and in mid position, and means for moving said chamber in a path conforming in curvature to said bottom Wall, the length arcuately of sa'id bottom wall so exceeding the chamber movement that said media do not engage the end walls of said chamber when unaccompanied by material in said chamber, andV means for introducing material into said chamber while the latter is in motion.

30. In a mill. a support, an element pivotally mounted on said support and oscillating like a pendulum rapidly during milling and having an arcuate chamber formed therein having inn'er and outer, at least approximately concentric walls whose curvature conforms approximately to arcs of circles struck from its axis of oscillatory movement and end walls alternately engaging the chamber contents, and a free charge of size-reducing media within said chamber comprising elements of widely varying size classified in strata during the oscillation of said chamber with the larger elements traveling on the shorter radii, and means for admitting and discharging material relative to said chamber during chamber oscillation arranged to provide for passage of material as its size is reduced through said strata,

ROBERT S. BUTLER.

CERTIFICATE OF CORRECTION.y

Patent No. 2,168,082.

August 1. 1959.

ROBERT S. BUTLER.

It is hereby certified that error appears in the printed specification ofthe abovenumbered patent requiring correction as follows: Page 5,. second column, line Lil, for"oi Fig." read in Fig.; line 14h, for "20v r `read 20H1; page 6, first column, line 8, beginning with "while I have" 'strike out all to and including the word and period "claims," inline 16', insert the same before I claim" inline 59, eamfpage `and column; page 9, first column, line 5l, claim 20, for "dimensional" read dimension;`1ines M8 and 50, claim 21, for "substatnially" read substantially; and that the said Letters Patent should be read with this correction therein -that the' same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of March, A. D. 19,40. l

(Seal) Henry Van Arsdale, Acting Commissioner of Patents.

sage member extending upwardly from the upper wall of said chamber, a sleeve associated with the upper end of said feed passage member, surrounding the axis of oscillation of the chamber. a fixed feed spout, a guard member associated therewith, in relatively rotary shielding relation with said sleeve, said guard member and sleeve being apertured in line withA each other. the apertures of the sleeve and guard being of sumcient size and their relative movement such as to maintain a feed connection between said feed spout and said sleeve of constant cross sectional area.

28. In a reduction mill, an elongated reducing chamber having end walls and longitudinally extending top, bottom and side walls and of approximately uniform cross sectional area between the end portions thereof, means for feeding material thereto including a feed aperture in, and adjacent the central portion of, one of said longitudinally extending walls of said chamber, discharge apertures in another longitudinally extending wall of said chamber, the walls of said chamber imperforate save for said feed and discharge apertures, means for supporting said chamber for oscillation about an axis from which it depends, means for imparting a predetermined longitudinal bodily oscillation to said chamber about said axis, said chamber so formed that the end portions thereof are spaced from each other by less than the length of said chamber along its center line and the end portions of said chamber being upwardly extended relative to the central portion thereof to such a degree that during chamber oscillation the extremities of said chamber are both at all times higher than the lowest intermediate portion thereof, and a charge of free reducing media confined in said chamber by the walls thereof and movable bodily with and also relative to said chamber and insufficient in volume, in relation to the length of excursion of said chamber. to engage either of the chamber ends when the mill is running below a predetermined minimum load.

29. An oscillating size-reducing chamber having upwardly concave arcuate top and bottom walls and further having end walls which alternately engage the chamber contents once in each cycle during milling, said chamber containing a charge of freely movable size-reducing media all of which are free to move relative to each other in any direction except as restricted by the chamber walls and each other and whose most remote elements are spaced from each end of the chamber when the latter is stationary and in mid position, and means for moving said chamber in a path conforming in curvature to said bottom Wall, the length arcuately of sa'id bottom wall so exceeding the chamber movement that said media do not engage the end walls of said chamber when unaccompanied by material in said chamber, andV means for introducing material into said chamber while the latter is in motion.

30. In a mill. a support, an element pivotally mounted on said support and oscillating like a pendulum rapidly during milling and having an arcuate chamber formed therein having inn'er and outer, at least approximately concentric walls whose curvature conforms approximately to arcs of circles struck from its axis of oscillatory movement and end walls alternately engaging the chamber contents, and a free charge of size-reducing media within said chamber comprising elements of widely varying size classified in strata during the oscillation of said chamber with the larger elements traveling on the shorter radii, and means for admitting and discharging material relative to said chamber during chamber oscillation arranged to provide for passage of material as its size is reduced through said strata,

ROBERT S. BUTLER.

CERTIFICATE OF CORRECTION.y

Patent No. 2,168,082.

August 1. 1959.

ROBERT S. BUTLER.

It is hereby certified that error appears in the printed specification ofthe abovenumbered patent requiring correction as follows: Page 5,. second column, line Lil, for"oi Fig." read in Fig.; line 14h, for "20v r `read 20H1; page 6, first column, line 8, beginning with "while I have" 'strike out all to and including the word and period "claims," inline 16', insert the same before I claim" inline 59, eamfpage `and column; page 9, first column, line 5l, claim 20, for "dimensional" read dimension;`1ines M8 and 50, claim 21, for "substatnially" read substantially; and that the said Letters Patent should be read with this correction therein -that the' same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of March, A. D. 19,40. l

(Seal) Henry Van Arsdale, Acting Commissioner of Patents. 

